This invention relates to a load-control and power-distributing system with a cycler for controlled loads which is operated whenever the demand exceeds a predetermined amount.
Electrical loads in factories, institutions and private homes are subject to appreciable daily fluctuations and seasonal variations. Power consumption charges for industrial consumers are usually computed on the basic maximum demand established by the consumer's basic requirements during the period under consideration. To lessen the effect of instantaneous loads of excessive magnitude, it is customary to use a maximum demand figure that has been averaged over periods varying from fifteen minutes to perhaps thirty minutes by means of suitable demand meters. More often than not, the financial charges to the power consumer are combined functions of both the averaged maximum demand and the total energy consumption during the period for which these charges are computed.
Although off-peak water heating with a separate meter is well known, the use of demand meters has not in the past been common in private homes. However, the use of large loads, such as electric space heating, in homes may eventually make the use of a demand type rate structure desirable. Because of a thermal time constant in buildings, it is possible to enable the heaters at controlled time intervals and, as is known in the field, thereby effect a significant lowering of the electrical demand. It is further known that essential service loads, such as lighting, stoves, and most electromechanical machines all give off heat in amounts equal to the electric power which they consume. These types of loads contribute to the total building heat much in the manner of standard space heaters. Consequently, when these essential loads are on, the space heating load can be reduced by an equal amount (so as to maintain a constant demand) without affecting the comfort of the occupants.
The description of a load-stabilizer having a sequential order of priority is described in T. Wildi U.S. Pat. Nos. 3,133,202 issued May 12, 1964, 3,291,998 issued Dec. 13, 1966 and 3,489,913 issued Jan. 13, 1970. The last of these patents also described a cycler as used in combination with a load-stabilizer to give equal priority to space heating loads.
While the load-stabilizer has been successfully applied in a number of different basic applications for commercial and industrial power consumers, as well as in apartment buildings, the known types of stabilizers would be unduly expensive if used for private homes or small commercial applications.